The present invention relates to a III-nitride heterojunction power semiconductor device.
III-nitride heterojunction power devices are well known. A typical III-nitride power semiconductor device includes a drain electrode, a source electrode and a gate electrode disposed between the drain electrode and the source electrode. The gate electrode controls the current between the source electrode and the drain electrode. To control the current in a high power application, a large negative voltage is applied to the gate electrode in order to change the voltage at the gate electrode rapidly. When a large voltage is applied to the gate electrode rapidly, a high voltage develops between the gate electrode and the drain electrode. The gate may be damaged if the voltage between the gate and the drain electrode exceeds the breakdown voltage of the gate.
The breakdown of the gate is facilitated by the development of large electric fields around the gate. Thus, it is desirable to reduce the intensity of the electric fields around the gate in order to increase the breakdown voltage of the device.